of the spirit of the tree?  If the laws of matter and force alone account for the living organism, if we do not have to think of something that organizes, then how do we account for the marvelous diversity of living forms, and their still more marvelous power of adaptation to changed conditions, since the laws of matter and force are the same everywhere?  Science can deal only with the mechanism and chemistry of life, not with its essence; that which sets up the new activity in matter that we call vital is beyond its analysis.  It is hard to believe that we have told the whole truth about a living body when we have enumerated all its chemical and mechanical activities.  It is by such enumeration that we describe a watch, or a steam-engine, or any other piece of machinery.  Describe I say, but such description does not account for the watch or tell us its full significance.  To do this, we must include the watchmaker, and the world of mind and ideas amid which he lives.  Now, in a living machine, the machine and the maker are one.  The watch is perpetually self-wound and self-regulated and self-repaired.  It is made up of millions of other little watches, the cells, all working together for one common end and ticking out the seconds and minutes of life with unfailing regularity.  Unlike the watch we carry in our pockets, if we take it apart so as to stop its ticking, it can never be put together again.  It has not merely stopped; it is dead.

The late William Keith Brooks, of Johns Hopkins University, said in opposition to Huxley that he held to the “old-fashioned conviction that living things do in some way, and in some degree, control or condition inorganic nature; that they hold their own by setting the mechanical properties of matter in opposition to each other, and that this is their most notable and distinctive characteristic.”  And yet, he said, to think of the living world as “anything but natural” is impossible.

VIII

Life seems to beget a new kind of chemistry, the same elements behave so differently when they are drawn into the life circuit from what they did before.  Carbon, for instance, enters into hundreds of new compounds in the organic world that are unknown in the inorganic world.  I am thus speaking of life as if it were something, some force or agent, that antedates its material manifestations, whereas in the eyes of science there is no separation of the one from the other.  In an explosion there is usually something anterior to, or apart from, the explosive compound, that pulls the trigger, or touches the match, or completes the circuit, but in the slow and gentle explosions that keep the life machinery going, we cannot make such a distinction.  The spark and the powder are one; the gun primes and fires itself; the battery is perpetually self-charged; the lamp is self-trimmed and self-lit.